XWindowSystem: Specify mouse coordinates for resize in terms of the root window rather than the application window

modules/juce_gui_basics/native/juce_Windowing_linux.cpp

@@ -399,10 +399,9 @@ public:
 
     void clearWindowAssociation() { association = {}; }
 
-    void startHostManagedResize (Point<int> mouseDownPosition,
-                                 ResizableBorderComponent::Zone zone) override
+    void startHostManagedResize (Point<int>, ResizableBorderComponent::Zone zone) override
     {
-        XWindowSystem::getInstance()->startHostManagedResize (windowH, mouseDownPosition, zone);
+        XWindowSystem::getInstance()->startHostManagedResize (windowH, zone);
     }
 
     //==============================================================================

modules/juce_gui_basics/native/juce_XWindowSystem_linux.cpp

@@ -1790,7 +1790,6 @@ void XWindowSystem::setBounds (::Window windowH, Rectangle<int> newBounds, bool
 }
 
 void XWindowSystem::startHostManagedResize (::Window windowH,
-                                            Point<int> mouseDown,
                                             ResizableBorderComponent::Zone zone)
 {
     const auto moveResize = XWindowSystemUtilities::Atoms::getIfExists (display, "_NET_WM_MOVERESIZE");
@@ -1803,6 +1802,7 @@ void XWindowSystem::startHostManagedResize (::Window windowH,
     X11Symbols::getInstance()->xUngrabPointer (display, CurrentTime);
 
     const auto root = X11Symbols::getInstance()->xRootWindow (display, X11Symbols::getInstance()->xDefaultScreen (display));
+    const auto mouseDown = getCurrentMousePosition();
 
     XClientMessageEvent clientMsg;
     clientMsg.display = display;
@@ -1810,8 +1810,8 @@ void XWindowSystem::startHostManagedResize (::Window windowH,
     clientMsg.type = ClientMessage;
     clientMsg.format = 32;
     clientMsg.message_type = moveResize;
-    clientMsg.data.l[0] = mouseDown.getX();
-    clientMsg.data.l[1] = mouseDown.getY();
+    clientMsg.data.l[0] = (long) mouseDown.x;
+    clientMsg.data.l[1] = (long) mouseDown.y;
     clientMsg.data.l[2] = [&]
     {
         // It's unclear which header is supposed to contain these

modules/juce_gui_basics/native/juce_XWindowSystem_linux.h

@@ -242,7 +242,6 @@ public:
     bool isX11Available() const noexcept  { return xIsAvailable; }
 
     void startHostManagedResize (::Window window,
-                                 Point<int> mouseDown,
                                  ResizableBorderComponent::Zone zone);
 
     static String getWindowScalingFactorSettingName()  { return "Gdk/WindowScalingFactor"; }